The use of modular link conveyors in industry enjoys increasing popularity. Particularly for conveying food articles or consumer products, especially in packages or in semi-packaged form, the modular link conveyor represents the overwhelming choice of those in the industry looking for a long-lasting, low cost conveying solution. In the recent past, significant advances in the development of such have been made so as to provide more efficient handling of an even larger variety of food articles, packages and containers, as well as other types of articles and products.
One of the most popular types of modular link conveyor systems on the market today, if not the most popular, is manufactured and sold by the assignee of the present invention under THE DESIGNER SYSTEM and WHISPERTRAX trademarks, and illustrated and claimed in prior U.S. Pat. No. 4,953,693, Sep. 4, 1990 and U.S. Pat. No. 5,031,757, issued Jul. 16, 1991. Since the time of these early patents in the art, the significant advances have been fast in coming to provide an even more efficient operation and better handling and transporting of articles and products.
One such advance is the provision of rollers on the transverse connectors to allow for low back pressure operation, as shown in U.S. Pat. No. 3,669,241 to Chalich, U.S. Pat. No. 4,231,469 to Arscott, U.S. Pat. No. 5,330,045 to Hodlewsky, and countless others. The manifold past approaches all generally afford the desirable low back pressure necessary to prevent articles from becoming damaged, especially when the conveyor is operated in an accumulation mode. However, no provision is made for the efficient conveyance of articles in a direction different from the conveying direction (e.g., directly transverse to it), as may be necessary when diversion onto a transfer or takeaway conveyor is needed. Although forcibly moving lightweight or low-friction articles laterally across the chain is a possible solution, this increases the risk of damage, and really is not an, option when the articles are large or heavy, such as filled cartons, or have high-friction surfaces, such as tires.
In an effort to overcome the limitations inherent in these types of conventional roller chains formed of modular links, others have more recently proposed forming chains of modular links having a plurality of recesses in the conveying surface, each for receiving a correspondingly sized and shaped rotatable element. A current, commercially popular approach is shown in U.S. Pat. No. 6,148,990 to Lapeyre et al., which discloses the use of both barrel-shaped rollers and spherical balls as the rotatable elements mounted in correspondingly-shaped recesses formed in the conveying surface of the links.
Despite the seemingly advanced nature of this approach, limitations still exist. With respect to the links including the recessed rollers, performance remains limited by the fact that the conveying ability is generally unidirectional. The embodiments with spherical balls seemingly provide for omnidirectional conveyance, but the recess creates a deep pocket where debris and dirt can accumulate and bacteria may propagate. This makes the arrangement not well-suited for use in environments where sanitation is the primary concern (such as the conveyance of articles comprising food products).
Another limitation is that the spherical balls are recessed such that only a small amount of the surface is available for engaging the articles, which would otherwise tend to drag on the stationary link forming the vast majority of the conveying surface. Still another limitation is that the spherical balls may pop-out of the recesses under moderate shearing forces unless a separate cover is used. Losing even a single ball not only renders the links ineffective for use as intended, but also adds to the maintenance expense. The solution of providing a partial cover also complicates the overall assembly, adds to the manufacturing cost, and creates a protruding lip on which the articles may become caught during conveyance. Aside from the likelihood of damage, a caught article may also result in a deleterious jam, causing downtime and requiring costly manual intervention to clear. Since the entire surface of the spherical ball is exposed to the conveying surface during rotation, maintaining the proper lubrication in the corresponding recess to ensure smooth, reduced friction rolling contact may also be a limiting problem.
Accordingly, a need is identified for an improved modular link chain for use in conveying articles or objects capable of achieving low backline pressure, such as in an accumulation mode, and also allowing for the easy, efficient, and smooth diversion of articles in a direction besides the conveying direction.